<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div id="app">
        {{computedValue}}
    </div>
    <script src="./js/vue.js"></script>
    <script>
        const vm = new Vue({
            el: "#app",
            data: {
                value: 'panpanpan'
            },
            methods: {
            },
            computed: {
                computedValue: {
                    get() {
                        return this.value[0].toUpperCase() + this.value.substr(1)
                    },
                    set(val) {
                        this.value = val
                    }
                }
            }
        })
    </script>
</body>

</html>